By-products from crushing peanuts

Historic, archived document

Do not assume content reflects current
scientific knowledge, policies, or practices.

UNITED STATES DEPARTMENT OF AGRICULTURE

WASHINGTON, D. C. vV August 12, 1922

BY-PRODUCTS FROM CRUSHING PEANUTS.

| By J. B. Reep,! Assistant Chemist, Cattle Food Laboratory, Miscellaneous Division,
Bureau of Chemistry.

CONTENTS.
Page. | Page.
Peanut crushing industry....--- ee cseiersta| = 1 Products obtained from crushing peanuts.... 4
Crushing peanuts: Definitions of peanut products........-...-- 9
Wiarlebiestisediss scene ccc atk oe eas aeeeee 2 SS UTM IN QTY Re a eee one oe crc aia alas Sates lr Soave eee itl

IE TOCESS OS eee Se ee ees 2

PEANUT-CRUSHING INDUSTRY.

The popular idea seems to be that the peanut is marketed chiefly
in the roastedform. Asa matter of fact, however, these nuts are used
principally in making salted peanuts, peanut butter, and confectioners’
and bakers’ goods, and in the manufacture of oil and meal. The
peanut industry was of little commercial prominence until 1870, when
it began to grow gradually. By 1900 the quantities of peanuts raised
were increasing rapidly, and since 1915, when the crushing of peanuts
for oil and meal was undertaken on a commercial scale, the growth
of the peanut-crushing industry has been phenomenal. This growth
may be attributed to the fact that the peanut can toa large extent
take the place of cotton as acash crop in regions seriously infested
with boll weevil. Short cotton crops have placed the planters and oil
millers in large cotton-producing areas in an extremely difficult posi-
tion. The planters suffered from being deprived of a cash crop and
the oil millers suffered from having heavy investments in oil mills for
which there seemed to be no further use. The utilization of the
peanut for making oil and meal gave the planters a new cash crop
and enabled the millers to continue their operations.

1 Acknowledgment is made to G. P. Walton and L. E. Bopst, of the Cattle Food Laboratory, for assist-
ance in the analytical work.
108517 °—21

2 BULLETIN 1096, U. S. DEPARTMENT OF AGRICULTURE.

CRUSHING PEANUTS.
VARIETIES USED.2

The Spanish variety is the one grown principally for the production
of oul. The meats of this variety have a higher oil content than those
of any other, with the possible exception of the Valencia, or Tennessee
red. It has a higher proportion of meats to hulls than any other
variety and is adapted to a wider range of soil and climatic conditions.

PROCESSES.

Most of the crushing of peanuts is done in cottonseed-oil mills,
which are well adapted to this-work. These mills run for part of
the season on cotton seed, when it is available, and for another part
of the season on peanuts. Thus a close relationship exists between
the cottonseed-oil industry and the peanut-oil industry, although
many mills crush peanuts exclusively.

The processes for crushing peanuts in this country are of two dis-
tinct types—the hydraulic, which is intermittent, and the expeller,
which is continuous.

HYDRAULIC PROCESS.

From the storehouses to which they are brought by the farmers the
peanuts are run through shakers or conveyors having fine sieves, to
remove the sand and fine dirt, and then through larger sieves, con-
sisting of perforated plates haying holes large enough to permit the
peanuts to drop through, thus separating them from the sticks,
vines, stones, and larger pieces of trash, which pass out from the tail
of the machine.

The peanuts are next taken in screw conveyors to the huller.
Sometimes this is an ordinary cottonseed bar huller, or a slight
modification of it, consisting of a cylinder the lower part of which
is made of sharp-edged steel bars, with revolving sharp-edged bars
attached to a frame within. The peanuts are chopped as they pass
between the sharp edges, and the meats and hulls pass out through
slits between the bars. Most mills, however, use the so-called disk
huller. This consists of a cylinder the lower half of which is made of
steel bars properly spaced, having inside rough-faced disks, some re-
volving and others stationary, placed side by side, so that the revolv-
ing disks alternate with the stationary disks. Peanuts are fed in at the
top, the hulls are rubbed off as they pass between the disks, and the
hulls and meats pass out through the slits between the bars below.

The stock is next conveyed to a shaker machine, where the meats
are separated from the hulls by means of sieves ahd an adapter

2 A complete description of the varieties of peanuts grown in the United States is given in Farmers’

Bulletin 751, copies of which may be had on application to the Division of Publications, U.S. Department
of Agriculture, Washington, D. C. ;

BY-PRODUCTS FROM CRUSHING PEANUTS. 3

attached to the air-suction pipe which sucks the hulls away from the
meats. This adapter, which is funnel-shaped and flattened out to a
slit about 2 inches wide, extends from one side to the other of the

shaker overwhich the mixture of meats and hulls is passing. In some
mills only one adapter is used; in others several adapters are placed
side by side. By varying the speed of the fans and making other
adjustments, it is possible to separate practically all the hulls from
‘the meats or retain any desired amount. In the past the practice
has been to leave 10 or 15 per cent of the hulls in the meats for the

‘purpose of securing a satisfactory extraction. It has been found, how-
ever, that this is not necessary for a successful extraction. In fact,
the presence of the hulls prevents efficient extraction, for the reason
that they soak up oil like a sponge. Most up-to-date mills now
remove all hulls possible from the meats before crushing.

After the hulls have been removed the meats pass through rolls,
which crush them. In some eases the rolls that are employed in
crushing cotton seed are used, but usually they are modified by having
some of the smooth rolls replaced by corrugated rolls. The object of
crushing is to open the oil cells as much as possible, thus securing a
more efficient extraction.

From the rolls the crushed meats go to the cooker, where they are
tempered and cooked for the purpose of further breaking up the oil
cells.

From the cooker the material goes to the cake formers, where it
is made into cakes inclosed in hair cloth. The cakes are then placed

in the hydraulic presses and subjected to great pressure, which

presses out most of the oil, leaving a cake containing from 6 to 8 per
cent of oil. This cake is ground into meal. Usually some of the hulls
previously removed are ground back with it, to give meal containing
the desired amount of protein. The idea seems to be to produce
meal corresponding in protein content to the various grades of cotton-
seed meal.

EXPELLER PROCESS.

In the expeller process the peanuts are not subjected to cooking,

_ but are chopped and heated to some extent in a steam-heated conveyor

which carries the material to the expeller. Usually the hulls are not
removed, so that often the cake contains all the hulls. Some mills,
however, shell the peanuts and crush them, thus securing an excellent

_yirgin oil that needs no refining, but is merely filter-pressed. The
cake obtained in this way makes a meal having an exceptionally high

protein content and is the source of peanut flour.

3 Hulls are either left in cottonseed meal or are ground back in, to give a cottonseed meal of desired pro-
tein content.

BULLETIN 1096, U. S. DEPARTMENT OF AGRICULTURE.
SHELLING PLANTS.

Many mills run shelling plants in which the best nuts are separated
to be marketed as shelled peanuts. The seconds are either pressed
out separately or run in with the regular stock when the mill is
running on stock peanuts in the usual way. The principle of the sheller
is the same as that of the disk huller (p. 2), but in addition it has_
attached to it screens, shakers, and fans, so that the meats come out ©
almost entirely separated from the hulls. The machine is run to make
as many of the meats as possible come out whole. )

PRODUCTS OBTAINED FROM CRUSHING PEANUTS.

Some mills make feeds by grinding the peanut cake with peanut
hulls, hay, cottonseed meal, cottonseed hulls, etc., with the idea of |
utilizing the hulls, which have a very low feeding value. It may be |
possible to use the hulls in this way if the product is not to be shipped |
very far, but their shipment for any great distance is not economical. |

Meals containing from 45 to 50 per cent of protein are produced |
but seldom placed on the market. Meals containing ali the hulls, with |
a protein content of from 34 to 38 per cent, and meals containing |
an excess of hulls obtained from shelling sons or some other source —
are also found. Between these extremes are several grades. |

Some mulls run almost entirely on seconds, which they buy from |
shelling plants, and on the germ (known to the trade as the heart)
and skins, which they obtain from peanut-butter mills and peanut-
confection establishments. A low-grade oil and a low-grade meal are |
thus obtained. Although peanut skins do not contain much oil |
originally, those from peanut-butter mills are high in oil, which is
tried out from the meats and absorbed by the skins during the roast-
ing. Such skins contain from 20 to 30 per cent of oil. Product-
obtamed by crushing skins, germs, low-grade meats, etc., should nc
be designated as peanut meal: fee fone be iepeled S show the
true character. |

Fertilizers are among the valuable products obtained from the
crushing of peanuts. Peanut cake, however, is too valuable as a
feed to be used directly as a fertilizer. The ideal thing would be. to
feed all the peanut meal produced to animals, using the resulting
manure for fertilizer. Unfortunately, it is not always possible to
do this. For business reasons a great deal of peanut meal is sold to
the planters, who use it directly for fertilizing purposes. Often it |
seems advisable for the oil millers to buy the peanuts from the }
planters, giving them the peanut meal as part payment. The planter
brings in a load of peanuts and takes away a load of meal. In this
way the working capital-of the mill is reduced materially, while the —

BY-PRODUCTS FROM CRUSHING PEANUTS. )

farmer saves on his transportation of fertilizer. Although, from a
broad economic standpoint, it is not good practice to use either cotton-
seed meal or peanut meal directly as a fertilizer, this practice probably
will be continued on account of local conditions.

The unusual value of peanut meal as a feed for animals, which is
not generally recognized, has been reported by C. O: Johns and D.
Breese Jones,* who have brought out the important fact that the pro-
teins in this product are high in lysine.

Osborne and Mendel and other workers have shown that lysine is essential to the
growth of animals. Nutrition experiments indicate that the animal organism can not
synthesize lysine, which must, therefore, be provided in suitable quantity in the food
to Insure normal growth. Since the muscle substance of animals contains about 7
per cent of lysine, foods deficient in this essential amino-acid should be supple-
mented by the addition of other foods which contain a high percentage of lysine.
Wheat and corn, both of which contain but little lysine, should therefore prove more
efficient diets if supplemented by some food of high lysine content. Peanut meal
appears to be well adapted to this purpose. From a nutritive standpoint, it is one of
our cheapest foods and seems to possess no objectionable properties. Animalsfed on
it thrive and increase rapidly in weight. It therefore seems probable that corn and
wheat could be much better utilized and a considerable saving in the cost of feeding
eifected by supplementing these cereals with peanut meal.

Many samples of products obtained during the crushing of peanuts
for oil were analyzed. Most of the peanuts used for this purpose
were of the Spanish variety; a few mixtures of the Virginia Runner
and Spanish were analyzed. The results of the analyses are reported

m Lables 1 to 1).
TaBLE 1.—Pure peanut meals and cake from crushing shelled hand-picked peanut meats.

| |

Carnie Noe ake Ash Ether | protei 2 evra
ample No. oisture. sh. rotein. iber. ree
extract. extract.

ee | OO ee |

Per cent. | Per cent. | Per cent. Per cent. Per cent. | Per cent.

SI DAS ain 7.5 4.0 8.6 50. 6 4,7 24. 6
SU PAA tenn Sc 7.5 4,4 8.4 52.1 “EEC 22.6
PA PAE DE ta eae 6.5 4, 4 8.0 52a 4.5 24, 3

Average. .- (oe? 4.3 8.4 | 51.7 4,7 23.8

TABLE 2.—Products from crushing whole peanuts by the expeller process.

i Ether : : Nitrogen-
Sample No. | Moisture.| Ash. Sine Protein. | Fiber. nen

Per cent. | Per cent. | Per cent. | Per cent. | Per cent. | Per cent.

D9 252 Ste es 6.1 3.9 6.5 34. 4 PHM 22. 0
DA TRL a eee 5.8 4,3 6.6 36. 8 25. 8 20. 7
PA). Ao DaBOeL 6. 4 3.6 Ta 34. 7 26. 4 21. 7
BAS) eee ae eae ae 4,1 6. 4 BY ATE 22N2, 22. 4
BULDRIE en ee Orel: 4.3 10. 1 37. 6 22.3 20. 6
S204 ee 6. 6 3%, ) Tp? 38. 6 21.9 21.8

Average. . 6. 2 4.0 7.3 36. 6 24. 3 PAS

!
4 The proteins of the peanut, Arachis hypogexa: II. Distribution of the basic nitrogen in the globulins
arachin and conarachin. J. Biol.Chem. (1917), 30: 33-38.

6 BULLETIN 1096, U. S. DEPARTMENT OF AGRICULTURE.

TABLE 3.—Pure peanut hulls from hand-shelled peanuts.

Nitrogen-
Sample No. | Moisture.| Ash. ance Protein. | Fiber. free
: extract.

Per cent. | Per cent. | Per cent. | Per cent. | Per cent. | Per cent.

SI4COtes Bees 8.7 2.1 1.2 6.1 67.9 14.0
Sia OQIS eae 8.0 3.1 -8 GSits 64.5 17.9
SIA09 RS Shee sc (5 2.6 .6 5.6 65. 3 18.4
By De) eee 6.7 2. 2 1.6 5. 8 69. 7 14.0 =
SL280 Seer a 6.5 2. 4 1.0 5. 2 68. 4 16. 5
Be oo oeee 8.3 2.9 .8 4,4 70. 0 14.0
SIS022e ee = ee 6. 2 2.0 AS) 5..0 69. 3 17.0
SIZ04 See oheces 8.3 2.9 1.6 5.9 66. 3 15.4
SISLOe eee UBT 3.2 1.9 5.9 65. 6 11% 7
Sf? Rife see 6.9 2.6 6 4.6 68. 9 16.4
SSIS sae 6.0 2.9 tl 5. 0 68. 8 16.6
SIS28 ee eee 8.6 2k .6 4.8 68. 6 14.7
31330 st ee 1 .9 5.5 63. 5 20. 5
Average. - 7.5 2.5 1.0 5. 4 67.5 16.1

TABLE 4.—Peanut hulls obtained at the mills.

Ether Nitrogen-

Sample No. | Moisture.| Ash. : Protein. | Fiber. free
STE, | extract.
Per cent. | Per cent. | Per cent. |Per cent. |Per cent. | Per cent.
HNN sstssec Te ih 2.4 1.4 5. 6 70.0 | 13.5
SL290 Sse ee 8.1 2.8 25 6.8 61.6 | 18. 0
SIQOS Ree eee 8. 2 4.8 Daud) 6.1 64.0 | 14.2
BS Vilesseaecce 8.6 Sa ae 6.3 Gleae 17. 8
S18025235- 25-2 6. 2 2 -9 5.1 69.3 Lisi
ZU 202 Rees eee 7.8 2.9 6.5 7. 2 61. 2 14.4
IMR eassso GTS 8.5 2.9 .4 4.4 69. 6 14.2
29225 eee 8.3 2.6 .4 6.1 64.6 18.0
29263 =e yee 7.9 1.9 of 5.0 (Ale 13.4
293305265 -E ee 7.8 4.6 4.1 9.8 47.0 26. 7
QOSS Temeee ee 7.4 3.6 3.6 9.6 50. 7 Zoe
Bi Hae ee sae 8.1 2aik- 3.3 Ee 62.3 16.7
SIS0G S552 ee 8. 2 3.3 9 6.9 65.5 14.2
SISIGRES. ee Se 8.2 4.0 9.1 10.1 Ril 17.4
SSG ue Se 8.6 Be Th 7.8 5. 6 61.0 14.3
S320ee2 pee ae 8.5 Dail. 1,2 5. 4 66. 7 15.5
SIH secece 6.6 2.8 Pe, Pe 8.1 62.3 18.0
Shks eee aneaee 8.6 3.7 24:2 6.3 61.4 17.8
Average.. 7.9 3.0 2.9 6.8 62.3 U7f-il

TABLE 5.—High-grade cake and meal made by the hydraulic process from stock from which
hulls had been removed by suction.

Nitrogen-
Sample No. |Moisture.| Ash. | tT | protein. | Fiber. | free
: extract.

Per cent. | Per cent. | Per cent. | Per cent. | Per cent. | Per cent.

2926 eye eae sul 5.9 TES 46. 6 8.8 Za00
S125] see 6. 4 7.0 8.1 45.9 10.5 22.1
31252 eee 6.3 Use: 8.0 45.3 ie 22.0
312562 eee 7.8 5.0 Teac 46.5 10.5 2255)
Pay iene Re. 7.4 RS O87 47.2 8.8 21.6
SEZSS ee es 7.4 4.0 Chel 46.3 10. 2 25. 0
SL ZSQeRS os. 8.0 4.5 7.8 45.8 Me? 22010
SI286'5-5.45..805 6.9 4.6 10.5 48.3 8.1 21.6
3130722 eee 6.7 Dak 10. 2 47.1 9.5 21.4
S130 Ne toes 7.9 4.7 8.5 47.6 9.3 22.0
S131 2 Sosa eee 6.9 5.9 8.1 49. 0 7.4 2220
SHIGUW Que. oe. ey 7.1 53 9.4 48. 0 8.5 PAE YS
SBS es ne 7.9 9.6 6.9 46.5 4.6 24.5
S182 reas. 7.6 5. 4 8.0 45.9 10.8 22eo
Sloeiaeeoee 7.9 Fe 9.8 46.9 9.2 20. 7
Ola OF ence Tod 4.6 8.3 47.1 9.6 22.9

Average.. 7.3 5.6 8.5 46.9 9.5 22. 4

BY-PRODUCTS FROM CRUSHING PEANUTS.

‘

TaBLeE 6.—Peanut meals and cake of lower grade with different quantities of hulls left in or

ground in after

| Sample No. | Moisture.| Ash. Steric
}
Per cent. | Per cent. | Per cent.
: icra aera at 4.5 8.1
DOZ20 Sa 6.8 4.5 8.4
78 7, Vee 6.8 9. 2 9.2
2 eee eee 6.4 4.9 7.6
DOA ae ee 6.8 9. 9 8.2
29260 8. 258-28 7.6 5. 6 6.4
29530 ecco 7.3 8.1 8.7
31238 ..252 545 = 7.8 4.3 8.8
8107. Dees 8.5 3.2 5. 5
31291 2S es 5 8.0 4.4 6.8
31300: 24-2325. 7.4 3.7 11.4
31303. 2 x 252 <0 3.8 10.9
S13h eee 7.2 5. 8 7.0
SIS 25 NS 7.8 4.3 8.8
31399522555 8.3 2.0 8.8

TaBLE 7.—Peanut stock from which the hulls had

Ether

Oe

pressing.
l
Nitrogen-
Protein. | Fiber. free
extract.
Per cent. | Per cent. | Per cent
39.5 19.6 PAD.
38. 6 22 20.5 |
31.9 PAY: 19.7 |
38. 4 19.8 22.9
39.5 16.7 23.3
40.9 14. 2 25.3
38.8 16. 0 PAVE
43.3 hey; 24.1
28. 4 34.9 19.5
43.8 1522 21.8
34. 4 ZALo 21.6
34. 8 26.5 16.5
36. 7 24. 0 19.3
44, 4 12.9 21.8
| 43.4 iD Mal 24.7

been removed by suction

the. crushers.

‘ Nitrogen-| Hulls

Sample es Ash ier Protein. | Fiber. | free not re-
, 3 . extract. | moved.!

—__———_ |} J a

Per cent.| Per cent.| Per cent. |Per cent..| Per cent. | Per cent.|Per cent

4.4 2.8 45.7 28. ae 14.9 .0

< 4.0 De | 40.1 28. 8 10.6 13.8 212.0

6.9 2.8 46.1 29.8 3.5 10.9 aes

4.6 3.0 42.8 28. 2 8.4 13°07) 5.0

Jack 2.4 48. 0 27.6 4.0 i DAR ad

4.3 2.6 48.1 29.1 2.8 13.1 1.0

5.0 225 47.9 30. 2 2.6 11.8 1.0

4.5 PA 46.8 29.6 3.6 13.0 Dee

t Approximate.

2 Miller stated that this was not a good separation and was not normal.

TABLE 8.—Proportion of meats to hulls and of ‘‘pops” to normal peanuts.

}
| Sule Variety | Hulls. | Meats. | ‘‘Pops.’’
Per cent. | Per cent. | Per cent.
29230...| Mostly Spanish..........-.-- 25. 0 75.0 ee
29236... a ee a aS eee 24. 0 76. 0 1.3
29238. - - Spanish and Virginia Run- 26. 0 74.0 6.3
ner. }
29245...| Mostly Virginia Runner.. .-. 29. 4 70. 6 eee
29234...] Spanish and Virginia Run- RS 74.5 2.5 |
ner.
see Woes = = GO. 2s os eee 25.3 74. 7 3.07
29293...| Mostly Virginia Runner. -.-- 29. 0 71.0 6.3
pozesspanishe oe —___. ... 28. - 24. 0 76. 0 4.0 |
293355-— 1 eVirpinia Rimmer. 2.25.4 == - 29. 8 70. 2 5. 0
SAGER SODAMISH. se od ee aS eee 21.0 79. 0 .0
A= ee se 6 oa es = ae Ss a 23.4 76. 6 2.4
pi sOOLe ao iest te CGF SSeOLe: cep sot 229 77.5 3. 0
LZR Ee = Mees ae GOs eet PATE 78. 3 .6
P2922 5219552 42 Goes ees fet see sss PAYEE 76.9 1.2
30s eee COs e.g Fee FAD? 76. 8 8.4
aor) 22 2 3 Lo eee ee EO es 21.0 79. 0 3.8
abot Qos oss. = COSC 1 es io. ee ee 23.9 76.5 4.6
Biviye aA sss é 0: Sapeeeeks . Se at 22.0 78. 0 5.0
SESS 5| Esso COse 5255 2 ee ee 23. 0 77.0 .0
= eee ee ‘i RS Renee eer 22. 0 78. 0 2.4
B1398 | Spanish and Virginia Run- 23. 7 16.3 4.5
ner.
31402...| Virginia Rumner..........-.. PA fa | 72.3 10. 0
SMOG S ai S24 GOV 28555 . eee: Se 29. 0 71.0 2.2
38409...| Spanish and Virginia Run- 24.9 75.1 6.8
ner.
DASA Ere eee Satan oe ee ee eee 24.5 (Ea Wie EP ae RS
| ot SE a a ee ee ee 2 ee ee

on the way to

Sam-
ple
No.

29634
29145
31228
31229
31248

The ether-extract determination for the sample of skins removed

BULLETIN 1096, U. S. DEPARTMENT OF AGRICULTURE.

TABLE 9.—Peanut skins (‘‘red skins’’ or the coverings of peanut meats).

Ether Nitrogen-
Taken from— Moisture.| Ash. Ase aE: Protein. | Fiber. free
: extract.
| Per cent. | Per cent. | Per cent. | Per cent. | Per cent. | Per cent.
Peanut-butter plant, Virginia vari- 6.6 4,2 28. 6 Mile ail 9.1 30. 4
ety.
Peanut-butter plant, Spanish vari- ahi 2.8 28. 4 16.1 11.8 37. 8
ety.
Confectioners’ plant, Virginia vari- 7.3 3.4 30. 1 18,1 11.4 29.7
ety.
Peanut-butter plant, Spanish vari- 9.1 2.5 Slee 16.5 10.3 30.4
ety.
Peanut skins removed by hand, 9.3 3.0 4,5 ee 7 LS 59. 3
Spanish variety.
~ } !
TABLE 10.—Peanut germs (‘‘ peanut hearts’’).
|
Nitrogen-
Sample : Ether : :
Moisture.| Ash. = Protein. | Fiber. free
No. extract. extract.
Per cent. | Per cent. | Per cent. | Per cent. | Per cent. | Per cent.
31232 ee 4,5 2.9 45.5 28. 8 6.0 1203
31236... OT 3.3 45.8 29. 5 3.0 Ine 7
Av. 5. 6 3. L 45. 4 29. 1 4.5 12.0
TABLE 11.—Peanut meats.
if
| ; Ether : Nitro-
Sample No. |Moisture.| Ash. extract. | Protein. Fiber. | gen-free
7 é extract.
Per cent.| Per cent.| Per cent.| Per cent.| Per cent.| Per cent.
PAA a ie A | 4.3 2.3 48. 0 27.8 2.6 15.0
7B) ooEoese 4.4 2.4 48. 2 32. 2 6,33 10.5
S14 01a 4.3 293 47.8 29. 8 2.8 13. 0
31409 ae sess) 5.0 2nd, 47.1 31.4 23 12.0
S239 Ree ee 4.4 2.4 50. 4 28.5 ay 7 10. 6
Dl ZAG eee eee 5.4 2.0 47.6 30. 0 220. 85
S1249 Ss Nese 5. 6 2.6 45.6 29.6 3.2 13. 4
1250 sae 4.4 2.8 45.7 28. 7 323 byl
aR Ia2 8 Soe ese 4.9 2.6 45.5 29.9 2.6 14.5
SIS8saeeee. -- 5. 2 2.4 47.6 30. 4 2.9 ile
SP fessoodsos 5. 4 Zed 46.1 30. 6 3 12.5
SL280 pee oes 5. 2 2.6 46. 1 30. 6 2.4 13.1
SBS cosas 4.4 2.4 48. 2 29.1 2.6 118% 3)
313042252325 5.2 25 48. 4 29. 5 2.4 12.4
SSL eee 4.4 250 47.9 28. 9 2.5 13.8
StS (sees ee Sil 0 46. 0 29. 5 5S) iby, 7/
31318 e eee | 4.5 250 47.5 29. 5 2.8 13.2
SIAN eae oe he 4.5 2h 46.7 28. 6 Sak 14.4
SIS28-eee eee 4.5 2.4 47.1 ole 2.8 2a
Average. .| 4.8 | 2.4 47. 2 29.8 2.8 12.9
| <

by hand from the unheated peanuts is noticeably different from that
for samples obtained from peanut-butter plants and confectioners’

establishments.
was approximately 2.5 per cent.

cent of invert sugars and 2.4 per cent of nonreducing sugars.
The peanut germs analyzed (Table 10) were obtained at peanut-

butter plants and confectioners’ establishments.

On this sample the proportion of skins to meats
Sample 29145 contained 0.3 per

They are bitter,

BY-PRODUCTS FROM CRUSHING PEANUTS. 9

and the fat which they contain breaks up rapidly, becoming rancid,
making it necessary to remove them to secure a good product.

The peanut meats analyzed (Table 11) were shelled by hand from
_ peanuts obtained at the warehouse. Sugar and starch determi-
nations were made on one sample of Spanish variety peanuts, with
the following results:

Per cent
Rednemp sisars asin vert suvarg >. eet = eee es 0.3
INGETEd TCINT SHPAars 25 SUCTOSC. .o ee. . oe eee eee en 4.7
SUDA L ieee ees oe oe mare AI 4.7
PPnteeanters Ane Bharch.): “22 2c lee, Sn So 9.7

DEFINITIONS OF PEANUT PRODUCTS.

The Association of the Feed Control Officials of the United States
have adopted the following definitions for peanut products:

Peanut-oil cake is the residue after extraction of part of the oil by
pressure or solvents from peanut kernels.

Peanut-oil meal is ground peanut-oil cake.

Unhulled peanut-oil feed is the ground residue obtained after extrac-
tion of part of the oil from whole peanuts, and the ingredients shall
be designated as ‘“‘ peanut meal and hulls.”’

Peanut-oil meal, being the residue after extracting part of the oil
from the peanut Kernels, should contain no hulls. A product con-
taining a mixture of meal and hulls should be designated as such a
mixture. It is impossible, however, even in the most efficiently run
mills, to remove all the hulls by shakers and suction, which is the
usual commercial practice. A certain amount of hulls remains in
the stock as it goes to the crushers and a much larger amount in the
resulting meal. For instance, if the oil content of the stock is 48
per cent and the oil content of the meal is 7 per cent the meal will
have 1.8 times as much hulls as the stock which goes to the crushers. -
Under the present milling conditions, therefore, it is necessary to
permit the presence of a certain amount of hulls in a meal in order
that the definition may be practical. It follows that a method for
determining the percentage of hulls in a meal will be necessary for
control work.

A study of Tables 1 and 3 suggests two possibilities for methods
for determining the amount of hulls in mixtures of meal and hulls,
one based upon the crude-fiber content and the other upon the pro-
tein content. The average fiber content of hulls is 67.5 per cent and
the average fiber content of pure meal is 4.7 per cent. The average
protein content of hulls is 5.4 per cent and the average protein con~
tent of pure meal is 51.7 per cent, based on a moisture content of
about 7 per cent.

10 BULLETIN 1096, U. S. DEPARTMENT OF AGRICULTURE.

For the purpose of determining hulls from the fiber content and
from the protein content in mixtures of meal and hulls the following
formulas have been developed:

ForMULA 1.

Let X=the hulls
Then 100—X =the meal
675X +0.047 (100—X )=fiber
0.628. X +4.7=—fiber
y—iber—4.7

0.628
FORMULA 2.

Let X=hulls
Then 100—X=meal
0.054 X +0.517 (100-X )=protein
0.054.X +-51.7 —0.517.X =protein
—0.463 X =protein —51.7
51.7 —protein
ue eR

TABLE 12.—Basis for calculating hull content of mixtures of hulls and meal from fiber
and protein content.

|

|
Hulls. | Fiber. SEI) | ‘Hulls. Fiber. Protein Hulls. | Fiber. |Protein.|| Hulls. | Fiber. ‘ats, | Per. Pron | rons | rer. frten| os | rier. frotein| tae, | einer rote
.
Per ct.| Per ct. | Per ct || Per ct. Per ch. | Perct: |\_Perict- | Per c& Per ce. \\ Per crs | Perncts eerie
(We 2 a ea a | 26 \5'21-0- | 439ea 52. page| 2756 78 | 53.7 | 15.6
1 53 512 lS 27) 21.7) | SSSo 2S aes eee RNG a eon 79 | 54.3 115.1
2 G0 5048 i) -O8r 12953" | 38e7 HA 380 us| oor 80 | 54.9 | 14.7
3 G86" | 0a 29 | 22.9 | 38.3 557 | 39:2) 1) 2612 81 | 55.6 | 14.2
4 La2eals 49. 82-1 30° 2325.) Bis 56 | 39.9 | 25.8 | 82-956: Dalal
5 7.8 | 49.4 STi 23.25) 3728 57-1040: 5 4] 25.32 | 83 | 56.8 | 13.3
6 | 8.5 | 48.9 32 | 24.8 | 36.9 || 58 | 41.1 | 248 So) baa de ees
| FY 9G AE e4Qr 5 33 | 25.4 | 36.4 po | 41.8 | 24.4 85°) 58-04 12-3
em FE om ee cE 34 | 26.0 | 36.0 60 | 42.4 | 23.9 86 58: Ze died
QGP SP ais: oH) -Sa0 |) 26289: |> Soe 61 | 430) | 423.5 87 | 59.3 | 114
10: esl ieOes| Avot 36.4], 2%34) 3550) j|| eel. |e aoeGea ose 88 | 60.0 | 11.0
TE ATGs |S 4656 37 27.9 34.6 || 63 | 44.3 ik 89 | 60.6 10. 5
12a) i 464 3g | 28.6 | 341 ||. 64 | 449 | 22.1 90 | 61.2 | 10.0
13 EPO 457 39: |) 2952641 13336 65 4° 45:5 | 21.6 91 | 61.8 9.6
12 | 18 5 Bl. 4592 AQ I> 29.8 |\ 33:2 66is"| GAG tea ols ta 92 | 62.5 9.1
15 | 141 | 44-8 41 | 30.4 | 32:7 67 | 46.8 ¢| 20.7 |< aoa aI eke euRan
16 | 14.7 | 443 LOE | ey bi teal eRe 68 e474 20k? 94 | 63.7 8.2
17 | 15.4 | 43.8 AS BI. |Olsen | 69 | 48.0 | 19.8 | 95 | 64.4 Teer
18 | 16.0 | 43.4 44") 32.3 | 31536 0 SaO alee real tes a 96 | 65.0 Fee
19 | 16.6.| 42.9 45 | 33.0 | 30.9 Wt A492 O18. Sy 97 | 65.6 6.8
20 Laat) oe 46 3356)5)) S09taul 72 | 49.9 re | 98 66. 2 6.3
2) A798 | AMO 47 | 34.2 | 29.9 | 7 50.5 | 17.9 99 | 66.9 5.9
92 | 18.5 | 41.5 AS | 34.8>. | -2955eu Ga ated, el 178 100 | 67.5 5.4
BAP AG 3) ALA 4928935. 5 0 | 2900) a (PRES eT et ay at A |
24 | 19.8 | 40.6 50 | 36.1 | 286 |, eee, feoeaa| ious
US | Ogeae heap ct i Die Mes ogame Visser | Wf | -.53.0°+| 71620 | |
| } ! | } |

From the figures given in Table 12, obtained by applying these
formulas, 1t is possible to determine the hull content of a mixture
of meal and hulls from the fiber content or the protein content.
These determinations can be only approximations, since the fiber in
hulls and the protein in the meats vary somewhat. They are accu-

rate enough, however, to be of value in control work and are the
only measuring sticks for hulls known at present. The methods
are not sufficiently accurate to make it worth while to reduce the
products to an equal oil basis, as the oil in the meals does not vary

BY-PRODUCTS FROM CRUSHING PEANUTS. Tt

enough to make any material difference. Similar methods of calcu-
lation have been suggested in Texas Agricultural Experiment Station
Bulletin 22, ‘‘The Composition of Peanuts and Peanut By-products.”
The method based on the fiber content will probably be move accurate

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FIBER ~ PROTEIN

Fig. 1.—Relation of fiber content and protein content to hulls.

than the one based on the pr otein content, since hulls consist largely
- of fiber. From the curves in Figure 1 hulls can be determined at a
- glance from either the fiber content or the protem content.

12 BULLETIN 109%, U. S. DEPARTMENT OF AGRICULTURE.

The crushing of whole peanuts is usually done by the expeller —
process. The results in Table 2 indicate that a product containing |
from 34.4 to 38.6 per cent of protein is obtained. There seems to
be a tendency in the industry to consider this product as peanut —
meal, although it is not, but is peanut meal and hulls, as is also any
product which contains hulls over and above the amount that would
naturally be unavoidably left in the feed by an efficiently run mill.
Often manufacturers who crush by the hydraulic method and remove
all the hulls possible before crushing grind back into this product
either all the hulls or a part of them. They feel that such a product
is properly designated as peanut meal, although such is not the case.

The cause of the wide variation in the percentage of protein in
products obtained by crushing whole peanuts is the presence of
varying quantities of “pops” in the stock. These are pods which
contain no meats and are nothing more or less than hulls. Conse-
quently, when peanuts with a large proportion of “‘pops”’ are crushed
the resulting cake contains more fiber and less protein than that |
obtained from normal peanuts. If hulls are determined from the |
fiber and protein content by the formulas on page 10 a higher per- |
centage of hulls will be obtained than if the peanuts had been normal. |

The results in Table 5 show that in mills where hulls have been
removed by suction the meals obtained contain from 45.3 to 49 per ©
cent of protein and from 4.6 to 11.2 per cent of fiber, indicating from |
the fiber determinations the presence of from none to approximately _
10.3 per cent of hulls in the meals.

SUMMARY.

Crushing whole peanuts by the expeller process usually gives a |
meal containing from 34.4 to 38.6 per cent of protein. Crushing —
peanuts from which the hulls have first been removed by the hydraulic |
process gives a meal containing from 45.3 to 49 per cent of protein. |

Peanut meal is an excellent feed. Peanut hulls, however, have a
low feeding value and can not be economically shipped any great
distance for use as a feed.

It is possible to determine approximately the percentage of hulls
in a mixture of peanut meal and hulls, either from the fiber content
or from the protein content. It is probable, however, that the figures |
obtained from the fiber content will be more nearly accurate. |

The composition of peanut skins removed by hand differs from |
that of peanut skins obtained from the peanut-butter plants. The |
composition of peanut germs is similar to that of the meats, with |
somewhat lower oil and somewhat higher ash contents. |

A sample of meats from the Spanish variety of peanuts was found —
to contain 5 per cent of sugars and 4.7 per cent of starch.

WASHINGTON : GOVERNMENT PRINTING OFFICH : 1922